Tuberculosis

Classification, Pathogenesis, Diagnosis and Control of Tuberculosis

1. tuberculosis M.J. AFRA II BSC MICROBIOLOGY THASSIM BEEVI ABDUL K ADER COLLEGE FOR WOMEN

2. It is one of the lower respiratory tract infections It is a progressive granulomatous disease of the lungs. It is an ancient disease found in early mummies The infectious nature of tuberculosis was established by VILLEMIN and the causative agent was first described by ROBERT KOCH INTRODUCTION

3. KOCH named the causative agent as mammalian tubercle bacilli It is caused by Mycobacterium namely, Mycobacterium tuberculosis (in humans) & Mycobacterium bovis (in animals) INTRODUCTION

4. The causative agent is Mycobacterium tuberculosis Acid – fast bacillus due to mycolic acid present in the cell wall Fairy large, Non-motile, Rod shaped bacterium Non- Sporing and Non-Capsulated In tissues, thin, straight rods, in pairs or in clumps CAUSATIVE AGENT

5. Weakly gram-positive Obligate aerobe and slow grower with generation time of 6 – 12 hours Optimum temperature = 37 degree C and pH = 6.4 – 7 Grow only in media containing egg, aspargine , potato and serum CAUSATIVE AGENT

6. CLASSIFICATION

7. Impermeablity to stains and dyes Resistance to many antibiotics Resistance to killing by acidic and alkaline compounds Resistance to osmotic lysis via complement deposition Resistance to lethal oxidation and survival inside the macrophages VIRULENCE FACTORS

8. The infection occurred by the airborne transmission of droplet nuclei containing a few viable cells of virulent organism After the inhalation of the droplet nuclei, the bacilli are deposited in the alveolar spaces of lungs, where they are non-specifically engulfed by alveolar macrophages are not activated and so are unable to destroy the intracellular organisms PATHOGENESIS

9. The lymphocytes, specifically T cells, recognize the antigen processed and presented through MHC molecule This results in the T- cell activation and release of cytokines and other factors CD4+ cells produces gamma interferons that activates the macrophage and enhances the mycobactericidal capabilities of CD4+ cells These cells can limit the replication of intracellular M. tuberculosis and may kill the bacilli pathogenesis

10. Activation of the macrophages can result in bacterial killing while cytotoxicity may release bacteria from the phagocytes and allow their engulfment and destruction by activated macrophages Tuberculosis is of three types namely, DISSEMINATED, REACTIVATED, MILIARY PATHOGENESIS

11. Chronic productive cough Low-grade fever Night sweats Fatigue Weight loss And many complications in kidneys, bones, joints CLINICAL MANIFESTATION

12. The prevalance of clinical tuberculosis among the homeless in the United States maybe upto 300 times higher than the national average rate In recent years, the incidence of disease in the racial minorities in the United States has been more than five times than that observed ePIDEMIOLOGY

13. Infected individuals can be diagnosed with the help of the intradermal PURIFIED PROTEIN DERIVATIVE (PPD) skin test The mantoux test requires the intradermal injection of a measured volume containing a specified quantity of PPD The transverse diameter of induration is measured 48 – 72 hours later LABORATORY DIAGNOSIS

14. In a person with symptoms suggestive of tuberculosis, clinical specimens such as sputnum , bronchial washings, pleural fluid, urine or cerebrospinal fluid should be collected Sputnum should be collected in the early morning SAMPLE COLLECTION

15. DNA probes, gas-liquid chromatography, HPLC, and thin layer chromatography allows the identifications of a few species of mycobacteria within hours after sufficient growth is present on solid or in liquid medium DIAGNOSTIC METHODS

16. First line anti mycobacterial drugs and isoniacid , rifampin, pyrazinamide, and ethanobutol Streptomycin was one in the combination Combined drugs also used, and is used to reduce the resistance nature of pathogen This combined therapy is administered for 12 – 24 months TREATMENT

17. Vaccine against tuberculosis is available It is called as BGC (bacillus of calmette ) These strains are remained avirulent for about 60 years It is not 100% effective 60% - 80% effective rates in children CONTROL

18. THANK YOU References: rajan’s medical microbiology book